1. Field of the Invention
This invention generally relates to the field of managing rights to access secure digital data modules, and more particularly relates to an extensible method and system to enable specification of different types of digital property rights to secure digital data modules.
2. Description of Related Art
The developments in electronic communications and digital processing of data that comprise multi-media presentations have greatly increased the distribution of multi-media presentations in digital form. Digital audio, including commercial music recordings, have been distributed on Compact Disks (CDs), for some time, but the inability to practically store or communicate these relatively large data sets has precluded widespread copying and distribution of digitized media. Advances in economical storage, high-speed communications and playback of a large amount of digital data has led to digitizing of video productions, including motion pictures, and distributing data sets that contain these types of productions on Digital Video Disks (DVDs) as well as via electronic communications. Technology advances have also allowed the practical copying of these digital multi-media data sets onto writable media or the communications of these data sets among numerous people. The ability to reproduce original copies of digitized multimedia presentations, coupled with the recent ability to conveniently store and/or communicate the data, has lead to an increase in the copying, pirating and unauthorized sharing of digitized multi-media presentations. This unauthorized copying and distribution of digitized multi-media presentations has resulted in large losses to the owners of the copyrights in those presentations.
Various techniques have been used to try to prevent unauthorized copying of multi-media presentations. The data set that comprises the multi-media presentation, the media data set, is encrypted using the various techniques known in the art. Encryption of the media data set has limited effectiveness since the equipment that “plays back” or presents the multi-media presentation to a user must decrypt the media data set to allow playback, thereby requiring dissemination of the encryption technique to all product manufacturers. The commercial grade encryption techniques are also subject to development of decryption algorithms. The encryption technique used for video DVDs, for example, has been compromised by public release of a decryption algorithm used in DVD players. The publicly owned base of existing DVD players precludes changing the encryption algorithms used for that media once an encryption technique is compromised. Encryption protection by itself in existing player systems is also limited to authorizing access to the media data set and is not able to provide flexible limitations on the types of usage rights that may be granted to the media data set. Different types of usage rights that an owner of a media data set is interested in controlling include the right to modifying the data, immediate access to the entire media data set instead of progressive access over the course of the multi-media presentation, or access to permit deletion of parts of the media data set. Encryption of other types of data, such as a database or financial document, similarly fails to provide the ability to control the type of accesses or usages that may be authorized for the data.
Alternative protection techniques have been developed which support controlling different types of usage rights for a media data set. These systems, referred to as Digital Rights Management (DRM) Systems, are able to restrict access to data sets by limiting authorization to one or more types of usages of a data set in response to specified usage conditions. Access control in these systems is controlled through specified Digital Property Rights (DPRs). An example of a DPR is a right to only read a particular media data set for a specified number of times. Such a DPR may be used to provide a free or low cost demonstration of the multi-media data set. Existing systems support a variety of conditions on usage of the media data set and those conditions may be specified on a remote license server, but the available types of usages that may be authorized are fixed by the implementation and may not be flexibly varied by the owners of the copyright on a media data set.
Therefore a need exists to overcome the problems with the prior art as are discussed above, and particularly for a DRM system which provides flexibility to digital multi-media copyright holders in defining the type of usage rights that may be granted to their media and the usage conditions which must be satisfied prior to granting those types of rights.